One common way to liven up beverages is to add a slice of lemon or lime, but perhaps less common is to freeze the lemon or lime slice and use it in lieu of an ice cube to chill your drink.

Although you could freeze the slices in water using a cupcake baking sheet, you can just skip the baking sheet altogether. Just lay the lemon or lime slices flat on a tray in the freezer—they freeze perfectly well on their own. This was mentioned in a very old 1998 edition of Cuisine magazine (dug up by Gourmet Chef). Skipping the water part has an added benefit: You can use your lemon/lime "ice cubes" in drinks you don't want watered down, such as soda, iced tea, cocktails, or beer.